In Alphacam......you don't. They create one for you. You try it, and when it doesn't work you tell them what went wrong......then wait for them to fix it and send it back to you.
Unless you have a machine exactly like one that has already been done.......you will likely repeat the above process many times.
Planit is a giant pain in the rear to deal with. They may kiss your butt while trying to make the sale, but you will be lucky to speak with someone directly after that. And you will need to. I have integrated several Cabware and CabVision packages to machines for people that did not want to pay the ridiculous amount that Planit wanted to do the job. It was an absolute joke, and until we got a hold of the salesman and made a huge stink......we got nowhere. They would only respond to us by email or fax at their leisure. They sold both of these customers packages without working activation codes and it took nearly a week of back and forth email and fax before they got it right. There is an onion skinning bug in V7.5, and even though I have spoken to other owners who have experienced the same thing, Alphacam gave me the runaround telling me it was my computer until I finally gave up. My 10 year experience with Planit was lackluster at best. Alphacam is powerful......but you may not need the things that make it shine.
In Rhinocam.......you have a user configurable post. Its pretty easy to use, but you must know your machines code requirements very well to be able to tailor it properly. Rhinocam has a lot of preconfigured posts, but I didn't have one that worked right from the start for our Onsrud. If you can't get it right......you'll have to follow the same procedure as Alphacam as far as the back and forth goes. I never spent any time trying to fix anything with them, so i can't say how their service is.
If you are just cutting profiles, cutouts, and don't do any 3d work......the Rhinocam basic pack will do fine.(around 1000.00) Plus the cost of Rhino.....another 1000 unless you're a student.
As a former user of both......I wouldn't buy Alphacam unless I was going to be nesting......as that's pretty much all I used it for once I got to use Rhinocam.
One big plus for Alphacam was the speed at which it created a requested toolpath. Some complicated 3d stuff might take 15 minutes to generate in Rhinocam. Alpha was almost instant by comparison. This was on a 4gb dual core 3.0 mhz XP machine.
Rhinocam won't output for multi spindle drill heads that are popular on most routers......but that's probably not a big deal for stone.